1. Field of the Invention
The present invention relates to the field of copper clad, zirconium alloy tubes useful as fuel for nuclear reactors, and in particular to the provision of a barrier between the zirconium alloy and the copper lining to prevent diffusion of copper into the zirconium alloy during the operation of the reactor.
2. Description of the Prior Art
Thin-walled zirconium alloy tubes are often used as cladding tubes for fuel for nuclear reactors. Such tubes may be internally lined or clad with copper to increase the resistance of the tube to stress corrosion induced by fission products. For neutron economy it is desirable for such lining to be relatively thin. One problem often encountered when such copper clad, zirconium alloy tubes are used is that during the operation of the nuclear reactor the copper from the lining may diffuse into the zirconium alloy tube so that after a time the copper lining loses its ability to protect the tube. A previously known method for preventing the diffusion of copper from the lining into the zirconium alloy tube involved the provision of a coating of zirconium dioxide on the zirconium alloy before the copper lining was applied. The principal disadvantage of such method, however, was that electrolytic deposition of the copper layer on the tube was not then possible. Instead it became necessary to deposit the copper on the tube using chemical methods which are considerably more time-consuming and expensive than galvanic methods. Another disadvantage of this known method was that the coating of zirconium dioxide on the zirconium alloy tube increased the difficulty of utilizing chemical methods for application of the copper layer because activating substances were necessary and harmful residues thereof had to be removed.